1. Field of the Invention
This invention relates to fluid drive conversion systems, and in particular, to a vertical axis windmill having a central space for maximizing the performance of the rotation of the foils, thereby enabling the system to generate multiple forms of usable energy.
2. Related Art
Windmills have been designed and constructed for ages as a means for harnessing the wind and converting that wind to power and other usable energy. While most windmills are horizontally arranged, certain windmills have a vertical arrangement of the sails, or foils. The advantage of the vertical windmill is that it eliminates any large height requirement and the need for a “tail.” However, there is a continual need to improve the vertical windmill design and improve its performance while at the same time simplifying its design.
In U.S. Pat. No. 4,197,055, titled “Vertical Axis Windmill” and issued to Campbell, a vertical axis windmill is disclosed having a plurality of sails connected to a vertical shaft such that the vertical pivot axis of each said sail is not centered along the width of the sail, but rather is optimally located approximately ⅓ the sail width from its vertical leading edge. See Campbell, FIGS. 1 and 4; Col. 3, Lines 13-26. In addition to the offset pivot point, the interior edge of each foil is in close proximity to the vertical shaft. See Campbell, FIGS. 1 and 4; Col. 3, Lines 41-44. Although the Campbell patent suggests that the windmill can be used to provide power for different types of work, the patent is void of any disclosure as to how the windmill generates such power. The patent only discloses that the windmill can be used to drive an alternator comprising a field coil and an amature. See Campbell, Col. 5, Lines 21-26. Most importantly, the Campbell windmill is limited, as most conventional vertical windmills, in that not all of the sails are contributing to rotating the sails and the vertical shaft at all times through one complete revolution. That is, during operation of the Campbell windmill, there is always at least one sail, an “inactive” sail, that is not contributing to the rotation of the sails and the turning of the vertical shaft. The inactive sail is typically that sail which is downwind from the direction of the wind and is “blocked” from the wind by the remaining sails. This inactive sail does not contribute to the generation of energy because of the lack of a central space between the vertical shaft and the interior edges of the sails. Without a central space, wind cannot move through the windmill to push the inactive sail from behind, thereby causing the inactive sail to not contribute to the rotation of the sails and the turning of the vertical shaft.
In U.S. Pat. No. 5,332,925, titled “Vertical Windmill With Omnidirectional Diffusion” and issued to Thomas, a vertical windmill is disclosed having multiple layers of aerodynamic stators and airfoils connected to a vertical shaft. The stators are designed such that they rotate out of the wind to reduce the destructive tendencies in high winds, and a motor and centrifugal force are used to brake the system and provide better control in high winds. In addition, the Thomas windmill activates a generator only when the winds reach a minimum pre-set level, and then the windmill is used to enhance performance of the generator. The disadvantage with this vertical windmill is that it requires motors and generators to work, thereby increasing the complexity and operation of the system. The stators also are designed to rotate out of the wind, thereby forgoing the maximum potential of the wind's energy. In addition, as with conventional vertical windmills and the Campbell windmill discussed above, the Thomas windmill also does not provide a system wherein each stator is productive throughout an entire revolution around the vertical shaft. There is always at least one “inactive” stator. The stators are designed to pivot into the wind and minimize the surface area of a stator exposed to the wind, thereby preventing the wind from pushing a stator from the back and preventing such a stator from contributing to the rotation of the vertical shaft and to the generation of usable energy.
Therefore, there is a need for a fluid drive conversion system using certain vertical windmill technology that efficiently and effectively harnesses a flow of fluid into usable energy. There is further a need for a fluid drive conversion system in which the pivotal movement of foils is restricted in order to improve performance. There is still further a need for a fluid drive conversion system wherein all sails, or foils, of the system contribute at all times to the rotation of the foils and the generation of usable energy.